* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Arial', 'Microsoft YaHei', sans-serif;
    background: #f5f5f5;
    min-height: 100vh;
}

/* 导航栏 */
.navbar {
    background: white;
    padding: 15px 30px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

.navbar h1 {
    color: #333;
    font-size: 24px;
    font-weight: 500;
}

.navbar .nav-links {
    display: flex;
    gap: 20px;
}

.navbar a {
    color: #666;
    text-decoration: none;
    padding: 8px 15px;
    border-radius: 4px;
    transition: all 0.3s;
    font-size: 15px;
}

.navbar a:hover {
    background: #f5f5f5;
    color: #333;
}

.navbar .user-info {
    display: flex;
    align-items: center;
    gap: 15px;
}

.navbar .username {
    color: #333;
    font-weight: 500;
}

.navbar button {
    background: #333;
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 14px;
}

.navbar button:hover {
    background: #000;
}

/* 主内容区 - Hero Section */
.hero-section {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: calc(100vh - 70px);
    padding: 40px 20px;
}

.hero-content {
    max-width: 900px;
    text-align: center;
}

.hero-content h1 {
    font-size: 48px;
    color: #333;
    margin-bottom: 20px;
    font-weight: 500;
    line-height: 1.2;
}

.hero-content .subtitle {
    font-size: 20px;
    color: #666;
    margin-bottom: 40px;
}

/* 开始按钮 */
.btn-start {
    display: inline-block;
    padding: 15px 40px;
    background: #333;
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-size: 18px;
    font-weight: 500;
    transition: all 0.3s;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.btn-start:hover {
    background: #000;
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
}

/* 特性展示区 */
.features {
    display: flex;
    justify-content: center;
    gap: 40px;
    margin-top: 80px;
    flex-wrap: wrap;
}

.feature-item {
    flex: 1;
    min-width: 200px;
    max-width: 250px;
    padding: 30px 20px;
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    transition: all 0.3s;
}

.feature-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.12);
}

.feature-icon {
    font-size: 48px;
    margin-bottom: 15px;
}

.feature-item h3 {
    font-size: 20px;
    color: #333;
    margin-bottom: 10px;
    font-weight: 500;
}

.feature-item p {
    font-size: 14px;
    color: #666;
    line-height: 1.6;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .navbar {
        padding: 15px 20px;
        flex-direction: column;
        gap: 15px;
    }

    .navbar h1 {
        font-size: 20px;
    }

    .navbar .nav-links {
        width: 100%;
        justify-content: center;
    }

    .navbar .user-info {
        width: 100%;
        justify-content: center;
    }

    .hero-content h1 {
        font-size: 36px;
    }

    .hero-content .subtitle {
        font-size: 18px;
    }

    .btn-start {
        padding: 12px 30px;
        font-size: 16px;
    }

    .features {
        gap: 20px;
        margin-top: 60px;
    }

    .feature-item {
        min-width: 100%;
    }
}

@media (max-width: 480px) {
    .hero-content h1 {
        font-size: 28px;
    }

    .hero-content .subtitle {
        font-size: 16px;
    }

    .btn-start {
        padding: 12px 24px;
        font-size: 15px;
    }

    .feature-icon {
        font-size: 40px;
    }

    .feature-item h3 {
        font-size: 18px;
    }
}